To crossfeed or not to crossfeed? That is the question...

Discussion in 'Sound Science' started by jasonb, Oct 21, 2010.
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  1. WoodyLuvr
    Jon Sonne likes this.
  2. 71 dB
    Thanks Jon Sonne! So nice to hear somebody appreciating stuff I write.
    I don't know if there is much anything else I can contribute since I have said pretty much what I know about crossfeed, but there is always more to learn…

    :gift: Merry xFEEDmas to everyone! :christmas_tree:
    ironmine and Jon Sonne like this.
  3. ironmine

    I am glad that you like Redline Monitor.
  4. 71 dB
    Spatial Wars

    Episode I: Birth of Recorded Sound
    In the end of the 19th century technical means to record sound are invented. The sound quality is very bad and monophonic, but necertheless selling recorded music becomes a profitable business in the beginning of the 20th century. The biggest problems are poor frequency response and range, poor dynamic range, strong distortion and short playing time. People don't think about spatiality. A quarter into the new century electric recording is invented. Stereophonic "live" sound had been demonstrated as early as 1881, but it took a half a century to have recorded stereophonic sound in the 1930's.

    Episode II: Stereophonic sound
    In the end of 1950's stereophonic sound finally makes it's way to consumer market. In order to sell people the wonder of stereo sound the recordings tend to have very strong channel separation, "ping pong" stereophony. Most of the time people listened to these recordings with stereo loudskeakers, and even if the sound image was far from the potential of stereophony, it worked and people where excited. Sound Engineers adapted an artistical style of wide stereo image created by hard amplitude panoration. This style fundamentally contradicted the principles of human hearing. It is the dark side of spatiality. Easy and quick compared to the real spatiality that is based on the proper combination of ITD, ILD and other spatial cues. Sound reproduction in general had many other problems at that time, so hardly anyone payed attention to spatial problems. So, people where seducted into the dark side of spatiality. Balance of the sound (between the ears) was suddenly flawed after thousands of ears of natural sounds and recorded monophonic sound.

    Episode III: Crossfeed
    Some smart people understood that excessive stereo separation is totally unnatural when listened to with headphones. People had been seduced to the dark side of spatiality with popular music and what not containing excessive stereophony, spatial distortion. Perhaps it was loudspeaker manufacturers behind this evil plot to make headphone listening unnatural and tiring? Perhaps not. Perhaps it was simply lack of wisdow and knowledge of the ways of human hearing. Anyway, wise people developped crossfeed to address the problem. In respect of reducing excessive channel separation it was a success, but most people were seduced too strongly to the dark side of spatiality. It was not easy to bring them back, perhaps not even possible. Many of them didn't want to hear their beloved ping pong recordings without spatial distortion. Some other people did trust the wisdom of crossfeeders and where more open minded. They where able to hear the benefits of more natural spatiality. After decades the debate remains and the spatial war continues.
    ironmine likes this.
  5. bigshot
    This isn't really an accurate description of acoustic recording and playback. Horn recording stripped off room acoustics since the horn could only hear to a distance of 15 to 20 feet. But phonograph instruction manuals told consumers to put their phonograph in the corner of a live sounding room to add natural spatial acoustics to the dry recording. The acoustic recording process captured clear and present sound with human voices. That's why singers like Caruso were so popular in recordings. With a loud tone needle, the dynamic range was incredibly wide. There are certain records that go from a natural whisper all the way up to the point where your ears ring. You don't hear this with electrical transcription, only wth acoustic sound boxes. The various record companies manufactured the records to suit the capabilities of the machine, and vice versa.

    When you play back a Victor Caruso record on a good quality acoustic Victrola, the playback horn acts as an exact mirror of the recording horn, projecting the image of the singer about five or six feet in front of the phonograph. It's like an aural hologram. The effect is uncanny making the hairs on the back of your neck stand up. The sound quality is definitely not bad. There was distortion, and surface noise but it was organic sounding and attenuated by the diaphragm, not irritating like electronic noise at all. Until the mid 20s, all phonographs were acoustic and phonograph technology advanced greatly until 1930. Victor introduced Orthophonic records in 1924 which were electrical recordings designed to be played on a machine with an exponential horn. The sound quality of this kind of acoustic playback was excellent. When you hear a record being played this way, you find yourself looking for the plug, but there isn't one. The exponential horn extends the low end response and projects the sound out, filling the room. It is quite definitely spatial because the horn and room lend spatial presence to it.

    Most people have no idea how sophisticated recording was in the acoustic era. That's because all they have heard is tinny sounding CDs that are transferred flat. They were never intended to be played that way. People in the teens and 20s used acoustic phonographs that were designed to decode and enhance the sound cut into the shellac, and they placed phonographs in a live room that added spatial presence and character to the sound. The idea was to play back natural sound, not necessarily record natural sound. That theory sound backwards to us today, but it actually worked very well.

    And of course Episode IV is multichannel audio. There was a record label that recorded the rolls royce of phonographs on the stage of a theater with great acoustics. It was encoded in matrixed multichannel sound and I'm told the results were amazing. I've never heard any of these because the matrix format is a dinosaur today, but the only way to really capture the sound of an acoustic phonograph at its best would be to do it in multichannel.
    Last edited: Dec 30, 2017
    Brahmsian and WoodyLuvr like this.
  6. pinnahertz
    Your "Episodes" are pretty far off, and your perspective of "Spatial Awareness" is entirely limited to the small-ish world of recorded sound, and not even accurate for that. In fact, spatial awareness, and even music composed specifically for sound source and direction, predates recorded sound significantly.

    Directional cues had already been written into antiphonal "call and response" church music of the late 1500's and early 1600's, showing composers such as Giovanni Gabrielli had full spatial awareness in composition, and expected the performances of his music, which included choruses located behind the audience, to expose his audiences to such spatial stimulus. In churches of the time it was not uncommon to have as many as four or more organ chambers, left, right, front, back, and even "swallows-nest" chambers located high overhead.

    In 1830, Hector Berlioz first performed the now audiophile staple, Symphonie Fantastique, which included, in the score, directions for off-stage oboe parts, establishing the "depth" dimension. A few years later in his "Requiem" he specified four orchestras in separate locations.

    In 1933 the Bell Labs stereo experiments established that multiple channels were required for accurate spatial representation, and they even specified that an array of an "infinite number of microphones" that fed an a corresponding array of "an infinite number of loudspeakers" could replicate the full spatial experience. That's 1933! And NOT recorded, their experiments were with live music transmitted over phone lines equalized flat to 15kHz. You may also recall that they determined that the absolute minimum number of speakers/channels required for accurate representation was 3, L, C, R. The outgrowth of those concerts and experiments was a relationship between Stokowski (who actually was involved in the experiments) and Disney leading to Fantasia, produced and presented in multichannel sound, something Disney himself cooked up by adding surround speakers. The film was released in 1940.

    To state that people didn't think about spatiality at the birth of recorded sound is simply ridiculous. Live music clearly already contained, and was composed specifically for spatial awareness, and Bell's experiments and the entrance of surround sound in film indicates that composers and media creators were already aware that their audience could appreciate spatial effects, something that is inherent in human hearing, and predates even Gabrielli. The fact that recorded media wasn't made available to consumers until 1950 has nothing whatever to do with anyone's spatial awareness!

    In your "Episode II", you inaccurately represent audio engineering of recording as fully hard-panned, widely separated stereo recordings as the "norm". Wrong. Sure, there are those recordings, and more of them from that time than later. Certainly there were more than a few stereo "demo" recordings that shoved wide channel separation in the face of consumers to sell the concept. But orchestral and classical music was not recorded that way, and many other recordings were also not. Again, the resulting base of recorded music is not an indication of "spatial awareness" as much as a necessity in selling a new concept: make it obviously different.

    And now you come to "Episode III", and this gem: "Some smart people understood that excessive stereo separation is totally unnatural when listened to with headphones. People had been seduced to the dark side of spatiality with popular music and what not containing excessive stereophony, spatial distortion."

    I'm not exactly sure what it is you're saying here, but based on your many other posts like this, I'd have to assume it is that only "smart people" understand that excessive stereo separation is wrong, and everyone else is stupid, and seduced to the dark side. Seriously? Have you no idea how offensive that statement is? And after everything we've argued about pages ago????

    You have continually defined what is right and wrong in recording with your own opinions that ignore any and all creative and subjective opinions of anyone else. I'm pretty sure the "98% of all recordings need crossfeed" fabricated statistic is just a post or two away from it's ugly reappearance. It's a complete exaggeration, and how could it be otherwise? The application of a rudimentary generalized crossfeed system must be varied according to the recording itself, and that requires...guess what?....subjective judgement....yes, opinion! And THAT means, your 98% stat is wrong.

    And what have we argued about? NOT that crossfeed is universally wrong. NOT that it doesn't provide a benefit. NOT that it should't be tried in all it's forms. It's the presentation of personal opinion as immutable fact that continues to be the problem here! Some may disagree with your fabricated terminology, statistics, and value of crossfeed, but if they do, they WILL be termed "stupid" or "seduced" by you! Do you have any idea how offensive THAT is? We've talked about the concept of grays, not blacks and whites. We've talked about the fatal flaws of rudimentary crossfeed, and that "crossfeed" itself doesn't even define a single thing, that its application must be variable from zero on up to some arbitrary 100% point, that HRTF is important, yet not uniform, and on and on.

    It's all been done, and done to death, right here in these pages.

    If everyone is so spatially unaware, or should I say "unenlightened", then why have we had the independent development of 3 multichannel immersive audio systems in the base few years? And, conversely, if crossfeed is so critical to life itself, where is it in the commercial market? It's so simple it should be on everything, but it's not.

    Until we all live in a police state that requires every headphone listener to employ your specific brand of crossfeed to 98% off all recordings, I'm going to take exception with your sweeping generalities, fabrications, inventions of concepts and terminology, and condemnations of anyone who has a different opinion. I believe there's room for crossfeed, and room for not using any, depending on the recording, and the listener's preference. I do NOT accept that rudimentary crossfeed is required for all recordings or our brains will be reduced to inert gelatinous masses. I do NOT accept that any simple crossfeed is better than none, or that it is impractical to do something better.

    I also have absolutely no doubt that the above labels me a complete idiot by some here. I would suggest neither idiocy nor fanaticism are a very long hike from each other....or from insanity.
    Brahmsian likes this.
  7. jgazal
    Thank you for sharing that!
  8. 71 dB
    Excessive stereo separation at the ears requires the lack of environmental acoustics AND very close sound sources. Giovanni Gabrielli and Hector Berlioz did not suffer from such conditions. Nobody needs to be aware of excessive separation if it doesn't exist and in the past it didn't. Music was always heard in a way that involved acoustic crossfeed. When you put headphones on your head you can create a situation where acoustic crossfeed doesn't exist or is too weak. That's when the problems theoretically start.
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  9. pinnahertz
    But you imply that with the onset of widely separated stereo mixes in headphones, people suddenly become spatially unaware. "Sound reproduction in general had many other problems at that time, so hardly anyone payed attention to spatial problems. So, people where seduced into the dark side of spatiality." Not true. The early highly separated stereo mixes were purposeful, intentional, deliberate, and achieved their goal, which had nothing whatever to do with a realistic spatial presentation in headphones! You're simply misapplying the medium, then complaining about how evil it is when listened to incorrectly. I'm surprised you aren't equally bitching about mono compatibility. Play some stereo recordings in mono, and it's all wrong again in a different vector. There's a method of remediation to that too, but no mention, huh?

    And not true there is such a thing as the "dark side" of spatiality, with all of those serious negative connotations. That's your spin.

    You also stated outright that there was no spatial awareness in the early days of mono recording, "People don't think about spatiality." Yes, they did. They were acutely aware of it, but had no practical means to present anything other than mono. There's a difference between being not being aware of something and simply not having the tools to deal with it.

    There is no such thing as acoustic cross-feed in live acoustic music. The fact that both ears hear variants of the same sound source is NOT cross-feed, it's spatial hearing.

    When you put headphones on the experience may result in an artificial representation of the intent of the creators, who built the mix to be presented in an acoustic environment. Or not, or anywhere in between. It depends on the recording. The theoretical problem is not universal.

    Please keep in mind that the application of cross-feed is not the correction of a problem (can't be, as you can't correct for something that is not known in detail, and without knowing the creators intent), it's a mitigation of a subjectively perceived problem that must be regulated based on subjective opinion relative to specific recordings.
  10. 71 dB
    When you hear excessive separation for the first time you can be seduced to the dark side.
    I have developped "vivid mono" for making stereo into mono.

    The problem is too much ILD (more than 5-6 dB at low frequencies) and ITD (> 640 µs). Applying crossfeed reduces these values. So, it is a correction to a problem.
    ironmine likes this.
  11. bigshot
    I think it's a lot more beneficial to just get a good speaker system.
  12. WoodyLuvr
    Beneficial to/for whom? Really depends on the end user and their particular listening environment. In my case, there is no speaker system in the world that would sound good and/or work as good as a pair of headphones. All relative.
    ironmine likes this.
  13. pinnahertz
    What "dark side"? Do I assume you have once again created your own definition, albeit borrowed from a certain other creative work?
    I cannot WAIT to hear what kind of nonsense that is!
    None of that defines creative intent.
    A "reduction" is not a "correction". A non-specific cross-feed cannot correct for an undefined problem. You figures do not define a problem as they do not include creative intent.

    The problem is evaluated as such subjectively by each individual listener who may determine what, if any, cross-feed makes a subjective improvement to his experience. What you evaluate subjectively as a horrific problem, someone else might evaluate as just fine, or anywhere in between. But nobody would be "correct" in their evaluation except for the actual creator/artist. And since you don't have them as a reference, your analytical application of a pseudo-correction would be a fabrication, a false correction of an undefined problem. Don't get me wrong, your "correction" may in fact be perfect for you, but don't force it on anyone else. The entire matter is subjective, there is no right/wrong.

    And no "dark side". That is another of your offensive labels. What if someone happens to like a recording, one of your 98%, without any crossfeed

    I can't quite say how offensive it is for someone to present their subjective opinions as a religious tenant to which, if you differ, you are condemned.

    If you want to win people to your side, present evidence that your process is an improvement. Don't bother with your theories, or attempting to justify your position by fabricating your own definitions, statistics or terminology. Just present actual examples to listen to, and let others form their own opinions. That's something that has yet to be done.
  14. bigshot
    Practicality, perhaps. Sound quality all things being equal, no. The best speaker setups trounce the best headphone setups. If you live in an apartment with grouchy neighbors, you have to make do though.
    Last edited: Jan 1, 2018
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